Realizing the Potential of 4D Printing

As additive manufacturing technology moves from research and prototyping to mainstream production, researchers are shifting their attention to producing structures that can transform in a pre-programmed way in response to a stimulus. The technology needed to create such products has been given the popular name “4D printing,” because it creates 3D objects that transform over time.

Programming structural deformations into physical objects is not new; researchers have been working with “memory materials” and “smart materials” for a long time. One of the most popular technologies is known as shape memory alloy, where a change of temperature triggers a shape change. Other successful approaches use electro-active polymers, pressurized fluids or gasses, chemical stimulus and even a response to light that reshapes the final product after manufacture.

Their approach was to print 3D structures combining materials with different properties: one that remained rigid and another that expanded up to 200% of its original volume. The expanding materials were placed strategically on the main structure to produce joints that stretched and folded like a “bendy straw” when activated by water, forming a broad range of shapes. For example, one 3D-printed shape resembled the initials “MIT,” but was designed to transform into another formation that looks like the initials “SAL,” which stand for Self-Assembly Laboratory.

Today, 4D printing is emerging as a further extension of additive manufacturing that has real commercial applications. According to analysts at Grandview Research, the global 4D printing market is only estimated to reach $64.5 million by 2019, but from there, it’s expected to grow at a compound annual growth rate exceeding 33.2 percent through 2025. The research firm attributes the rapid take-off to rising demand in the defense, aerospace, automotive, and healthcare industries...